Rosetta spacecraft meets asteroid Steins

Rosetta spacecraft meets asteroid Steins on 5 September 2008

ESA's Rosetta spacecraft will make a historic encounter with asteroid (2867) Steins on 5 September 2008. Steins is Rosetta's first nominal scientific target. The spacecraft will rendezvous with the asteroid in the course of its first incursion into the asteroid belt located between the orbits of Mars and Jupiter, while on its way to comet 67/P Churyumov-Gerasimenko.

The Swedish Institute of Space Physics (IRF) has two instruments on board Rosetta, an ion composition analyser (ICA) developed at IRF in Kiruna and a Langmuir probe (LAP) developed at IRF in Uppsala. Both are part of the Rosetta Plasma Consortium (RPC). The instruments will be turned on during the fly-by of the asteroid to see whether it disturbs the solar wind enough to be detectable from the spacecraft. IRF scientists say it is unlikely the instruments will see anything, but they will be checking the data with great interest.

The study of asteroids is extremely important as they represent a sample of Solar System material at different stages of evolution - the key to understanding the origin of our own planet and of our planetary neighbourhood. The closest approach to Steins is due to take place on 5 September at 20:58 CEST (Central European Summer Time), from a distance of 800 km.